I agree that natural gas is not a long term solution but I disagree that wind and solar can ever be enough. Back around the Thatcher years the Brits thought their North Sea gas would last forever. Now much of their gas comes from Siberia with the risk of the tap being turned off if other customers along the route displease Russia. Norway thinks its gas and oil will peak soon. Even Saudi Arabia is thinking of importing LNG. It is thought that fertilisers made from natural gas via ammonia processes enable world population to be a third larger than it already is. When diesel becomes expensive as oil depletes it is likely that trucks will convert to compressed natural gas as an alternative fuel. That will greatly increase overall demand for gas.

Another problem with gas fired electricity is that it will never achieve the 80% CO2 reductions we want long term. Since wind farms typically average 25% of their rated capacity and fast acting hydro is limited then gas generators need to cut in to maintain the grid. As total gas demand (truck fuel, fertiliser, domestic) increases that gas power will be increasingly expensive. Those other uses should get priority before gas is squandered on power generation. Ultimately we will have to replace them with alternatives eg synthetic fuel which won't be cheap. Some other form of affordable low carbon electrical generation will have to be implemented that doesn't need gas backup. We should conserve gas until that is sorted out.

I'm hopeful that wind and solar will one day power the world, when the distribution issues such as getting cables through the core of the earth can be resolved.
In that meantime we have a highly advanced highly efficient economic and safe alternative which for all intents and purposes does not affect the climate in any way: http://www.youtube.com/watch?v=e_CcrgKLyzc&feature=player_embedded

Despite Daniel B. Botkin being a professor something his figures are completely wrong, and demonstrably so. Even the most ardent of wind advocates will tell you that energy generated by wind costs 50 per cent more than conventional, and there is some evidence from the Danish and German grids that it is fact three times more expensive. You can pick what answer you want from that, but Botkin is on a different planet.
As for the 1 per cent of land surface figure I suspect that's completely wrong too but does he have any idea what that figure means? Wind towers have to be placed in windy spots (obviously) but very carefully sited otherwise they may consume more electricity than they use (has happened in the UK). Finding that many prime locations is a big ask, not to mention that its a huge area to be covered entirely by wind generators.
I should be use to the nonsense generated by wind advocates by now, but this sort of sloppy rubbish supposedly from an academic is really the limit.